Wei Hua Zhang

Soil Water Infiltration and its Affecting Factors

Through comparing and analyzing domestic and foreign research on soil infiltration in recent years, this article summarizes the research progress on soil infiltration, especially the innovation in theory, method and progress in practical use and gives the advantages and disadvantages among various methods. It can provide reference for the researchers engaged in the study of soil infiltration and efficient soil water utilization.

Review on Pedotransfer Functions for Predicting Unsaturated Hydraulic Conductivity

The soil pedotransfer functions (PTFs) provide an easily way to estimate the unsaturated hydraulic conductivity, and it predicts missing characteristics from already available basic soil data. In this paper, a review was made on the most common PTFs for the estimation of unsaturated hydraulic conductivity in recent years, including the methods of Rosetta, Rawls, Campbell and Vauclin. Based on the methods, a summary of necessary input parameters and basic properties of the PTFs was made to in this paper. Finally it was pointed out that the future study will focus on how to improve the accuracy and reliability of PTFs and the multi scale study.

A Comparative Study of Different Hydrological Model and their Application in Little River Catchment

Sacramento, SimHyd and Tank model were selected and their structure, principles and characteristics were briefly described. Then by taking Little River Catchment in Georgia, USA as an example, the rainfall-runoff process was simulated by using the Rainfall Runoff Library. The results showed that: Nash-Sutcliffe coefficient reached more than 80% and RE (relative error coefficient of the total runoff) of Sacramento model also meets the requirements. Considering the Sacramento model is the best one on the Nash-Sutcliffe coefficient, the model is selected as the optimal model of Little River Catchment in this study.As the catchment is located in the southeastern USA, with humid climate, and saturated storage-based runoff generation, which is similar to Chongqing region, it provides relatively good reference for Chongqing as well as the entire southwestern region.

Automated Analyzer, LOI and other Methods for Determination of Soil Organic Carbon

SOC as a significant quantity for the global carbon cycle, makes great sense in soil management and future climate scenario. With more and more researches carried out on SOC, methods used to the determination of SOC have being formed: automated analyzer, LOI and some others, such as using climate change information and remote sensing technique. The objective of this paper is to discuss advantages and disadvantages of automated analyzer (C-N analyzer) and LOI, and provide some references in selecting the appropriate measuring methods of SOC for the readers.

Infiltration Characteristics of Soil Moisture in Liangping County

In order to relieve water shortage, many countries develop water-saving industries and increase water use rate of irrigation. The research on soil water infiltration has important effect on infiltration and runoff, as well as for irrigation. The study carried out in Liangping district of Chongqing by using double ring infiltration method and exploring the reasonable infiltration model in the study area. The relationship of initial soil moisture and irrigation coefficient was studied as well. The results showed that: the Kostiakov empirical formula could simulate the process of soil water infiltration properly. The soil infiltration rate of Liangping is 0.0320cm/min in the selected location.

Effects of Water Trading on Main Crops in Beibei District, Chongqing

Water trading is an effective method for efficient allocation of water resources, so it is essential to assess the potential impacts of water trading before the establishment of water rights trading market. The improved water rights allocation method may low down the uncertainty, although there is lots of uncertainty in the water trading for agriculture. This study compared the effects of two-part deployment method on economic profits of main crops by Game Theory method. The results show that water trading may optimally allocate water resources, moreover, the total free market could increase economic profits as far as possible; the more water users participating in water trading, the more profits the water trading can bring.

Effect of Different Organic Matter Content on Soil Moisture Dynamics

Organic matter plays an important role in soil moisture variation. In order to know the effect of organic matter on soil moisture dynamics, this study compared the infiltration and evaporation of soils with different organic matter content. The results showed that increasing the organic matter content in a certain degree can suppress evaporation and infiltration of soil moisture, and hence improving water use efficiency. When the organic matter content reaches3.2%, effect of suppressing evaporation is most obvious.

Irrigation Coefficient Analysis and its Research Progress

Based on the definition of the irrigation coefficient, we discussed the main factors which affect the irrigation coefficient as well as the measures to improve the irrigation coefficient in agriculture. According to the variation and the different features of the irrigation coefficient in different regions and conditions, this article not only explores the basic way to improve the irrigation coefficient, but also gives measures including water apportion measures, management and engineering measures. The potential ability of improving the irrigation coefficient is analyzed preliminarily in the real situation of Chinese irrigation methods and techniques.

The Earth’s Critical Zone Science and its Research Progress

A promising and involving interdisciplinary concept-the earth’s critical zone science is introduced in this paper. Within the earth’s Critical Zone, the coupled chemical, physical and biological processes which define Earth’s weathering engine are driven by climatic, anthropogenic, and tectonic forcing. Followed by the concept and specific questions related to the critical zone were given. Finally, current research in order to understand the Critical zone was reviewed.

Water-Saving Technology in Irrigation

Water is a vital natural resource, which is becoming increasingly scarce around the world. The balance between water availability and demand has reached critical levels in many regions due to water demand increasing, and availability diminishing through drought and over-extraction. Water resources have been very important to us human beings since our ancient society. And the use of water in irrigation is a momentous part. Effective and productive irrigation requires the most appropriate water application strategies that take soil, climate, and farming operations into account. In addition to this, inputs used must be applied to where it is required without giving any harmful effects to the environment. In this study, we took a comprehensive consideration of the related records, summarized the methods of water-saving technology in the world for need.